Heat exchanger

ABSTRACT

Disclosed is a heat exchanger including a plurality of tubes through which refrigerants flow, the tubes being spaced away from each other, and a plurality of fins through which the tubes are perpendicularly inserted, the fins being spaced away from each other at a predetermined distance, each of the fin having more than four peak portions and more than four valley portions that are alternately disposed. Heights or depths of at least two peak portions or at least two valley portions being different from each other.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat exchanger, and moreparticularly, to a heat exchanger in which an inclined angle and an airflow varying element are structurally modified to effectively guide airflow along fins disposed between tubes up to rear ends of the tubes.

[0003] 2. Description of the Related Art

[0004] Generally, a heat exchanger is installed in an air conditionerand functions as an evaporator or a condenser for performing a heatexchange between a refrigerant and air. A fin-tube type heat exchangeris widely used among various kinds of the heat exchanger.

[0005] In the fin-tube type heat exchanger, the fins installed in a tubefor air flow are classified into a slit fin, a louver fin, and acorrugate fin that is formed in a W-shape.

[0006]FIG. 1 shows a conventional heat exchanger having the corrugatefin.

[0007] Referring to FIG. 1, a heat exchanger 1 includes a plurality ofcorrugate fins 10 spaced away from each other at a predetermineddistance and formed in a W-shape, and a plurality of tubes 30 disposedpenetrating the corrugate fins 10 at right angles and along which arefrigerant flows.

[0008] Here the fin 10 is provided with peak portions 12 and valleyportions 14 at which the tubes are not penetrated and which areintersected with each other at a predetermined angle, a plurality of fincollars 16 defining tube insertion holes through which the tubes areinserted, and a plurality of seats 18 formed in a concentric circleshape to support the fin collars 16.

[0009] Herein, the conventional heat exchanger having the corrugate finwill be described with reference to FIGS. 1 to 4.

[0010] Referring to FIG. 1, the heat exchanger 1 is a fin-tube type, anda plurality of fins 10 and a plurality of tubes are intersected witheach other in a perpendicular direction. The tubes 30 arranged in tworows penetrate the plurality of fins 10 in a perpendicular direction.

[0011] Each of the fins 10 is the corrugate fin (hereinafter,abbreviated a fin). Each of the fins 10 has a plurality of donut-shapedflat portions and a plurality of inclined portions that are defined bythe W-shape having a plurality of the peak and valley portions. The fins10 are installed on the tubes 30 in a longitudinal direction of thetubes 30, being spaced away from each other at a predetermined distance.

[0012] Referring to FIGS. 2 and 3, there is shown a detailed structureof the fin 10. The fin 10 is formed in a W-shape with the peak andvalley portions 12 and 14 that are alternately formed. That is, the fin10 has two side ends that are respectively defined by the valleyportions 14 a and 14 c. In case a plurality of fins 10 are used, thetubes 30 are arranged in two rows in a zigzag-shape in order to improvea heat exchange efficiency.

[0013] That is, each of the fins 10 installed on the tube 30 has twopeak portions 12 a and 12 b and three valley portions 14 a, 14 b and 14c, which are alternately disposed and connected by inclined surfaces.The shape of the fin 10 is symmetrical based on the longitudinal valleyportion 14 b. Central axes of the zigzag-shaped tube 30 pass through thelongitudinal center valley portion 14 b.

[0014] The fin 10 is provided with a plurality of tube insertion holes16 a, central axes of which correspond to the respective central axes ofthe zigzag-shaped tube 30. The fin collars 16 are elevated from the fin10 to define the tube insertion holes 16 a through which thezigzag-shaped tube 30 is inserted. The tube 30 surface-contacts an innercircumference of each collars 16.

[0015] The seat 18 is formed in a concentric circle shape around a lowerend of an outer circumference of the fin collar 16 to support the fincollar 16 and to allow air to flow in the form of enclosing the tube 30and the fin collar 16.

[0016] An inclined portion 20 is formed on the fin 20 around the seat 18to prevent the air flowing around the tube 30 from getting out of acircumference of the tube 30. The inclined portion 20 is inclined upwardfrom the seat 18 to the adjacent peak portions 12.

[0017] The seat 18 is located on a horizontal level identical to thatwhere the valley portions 14 are located. Heights and depths H1 and H2of the peak and valley portions 12 and 14 are identical to each other.That is, the H1 indicates the heights of the adjacent peak portion 12from the valley portions 14, and the H2 indicates the depths of theadjacent valley portion 14 from the peak portion 12. In addition, theinclined surfaces connecting the valley portions to the peak portionsare inclined at an identical angle.

[0018] FIGS. 4(a) and 4(b) are respectively front and rear views of thefin, in which the peak portions 12 and valley portions 14 depicted inFIG. 4(a) correspond to the valley portions 14 and peak portions 12depicted in FIG. 4(b), respectively.

[0019] When the air is introduced into the heat exchanger 1, the growthof a frost formed on an outer surface of the fin 10 is proportional toan amount of a heat transfer on the outer surface of the fin 10. At thispoint, the airflow speed is increased at the tube area as well as at thefin areas between the tubes 30 disposed in a longitudinal direction,thereby forming a high-speed airflow. As a result, the heat transfercoefficient is increased and the frost layer is quickly grown on thesurface of the fin 10.

[0020] In case the frost layer is grown on the surface of the fin 10,since the distance between the adjacent fins 10 is reduced, an airpassage area is also reduced. Due to the reduced area, the airflow speedis increased much more. As a result, the pressure drop of the air isincreased in a parabola shape as time passes. Further, the heat transferamount of the heat exchanger is also greatly reduced.

SUMMARY OF THE INVENTION

[0021] Accordingly, the present invention is directed to a heatexchanger that substantially obviates one or more problems due tolimitations and disadvantages of the related art.

[0022] A first object of the present invention is to provide a heatexchanger that can improve the heat discharge efficiency compared with aconventional heat exchanger in which heights of peak and valley portionsare identical to each other, in which heights of a corrugate fin formedbetween peak portions and valley portions on a left or right side of areference line, through which central axes of the tube perpendicularlypasses, become different from each other.

[0023] A second object of the present invention is to provide a heatexchanger including a fin bent in a zigzag-shape such that heights anddepths of outer peak and valley portions are greater than those of innerpeak and valley portions.

[0024] A third object of the present invention is to provide a heatexchanger including a fin bent in a zigzag-shape such that heights ofouter peak portions are greater than those of inner peak portions toincrease an air passage area, thereby increasing an amount of airflow.

[0025] A fourth object of the present invention is to provide a heatexchanger including a fin bent in a zigzag-shape such that widths ofinclined portions connecting a center valley portion to adjacent peakportions are less than those of other inclined portions.

[0026] A fifth object of the present invention is to provide a heatexchanger having a fin bent in a zigzag shape with a center valleyportion formed in a flat shape.

[0027] A sixth object of the present invention is to provide a heatexchanger including a fin bent in a zigzag shape such that depths ofvalley portions are less than heights of peak portions and an inclinedportion is formed extending from a seat to the peak portions to allowair to effectively flow along tubes inserted in the fin.

[0028] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

[0029] To achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, there is provided a heat exchanger comprising a plurality oftubes through which refrigerants flow, the tubes being spaced away fromeach other; and a plurality of fins through which the tubes areperpendicularly inserted, the fins being spaced away from each other ata predetermined distance, each of the fin having more than four peakportions and more than four valley portions that are alternatelydisposed, heights or depths of at least two peak portions or at leasttwo valley portions being different from each other.

[0030] Each of the fins comprises a plurality of fin collars disposedalong a longitudinal centerline of the fin, each of the fin collar beingelevated to a predetermined height to define a tube insertion holethrough which the tube is inserted; a plurality of seats each disposedon a lower end of an outer circumference of the fin collar; and anairflow guide portion formed extending from an outer circumference ofthe seat to the peak potions at a predetermined angle to allow air toflow along an outer circumference of the tube.

[0031] According to another aspect of the present invention, there isprovided a heat exchanger comprising a plurality of tubes through whichrefrigerants flow, the tubes being spaced away from each other; and aplurality of fins spaced away from each other at a predetermineddistance, each of the fin including a fin collar through which tube isperpendicularly inserted, a seat disposed around an outer circumferenceof the fin collar, and peak and valley portions alternately disposed,inclined angles of portions connecting the peaks with the valleys beingdifferent from each other.

[0032] According to still another aspect of the present invention, thereis provided a heat exchanger comprising a plurality of tubes throughwhich refrigerants flow, the tubes being spaced away from each other;and a plurality of fins spaced away from each other at a predetermineddistance, each of the fin including a fin collar through which tube isperpendicularly inserted, a seat disposed around an outer circumferenceof the fin collar, and peak and valley portions alternately disposed, atleast one of the valley portions being formed between the peak portionsin a flat shape having a predetermined width.

[0033] According to still another aspect of the present invention, thereis provided a heat exchanger comprising a plurality of tubes throughwhich refrigerants flow, the tubes being spaced away from each other;and a plurality of fins spaced away from each other at a predetermineddistance, each of the fin including a fin collar through which tube isperpendicularly inserted, a seat disposed around an outer circumferenceof the fin collar, peak and valley portions alternately disposed,inclined portions extending from an outer circumference of the seat tothe peak portions.

[0034] It is to be understood that both the foregoing generaldescription and the following detailed description of the presentinvention are exemplary and explanatory and are intended to providefurther explanation of the present invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this application, illustrate embodiment(s) of theinvention and together with the description serve to explain theprinciple of the invention. In the drawings:

[0036]FIG. 1 is a perspective view of a conventional heat exchanger;

[0037]FIG. 2 is a perspective view of a fin depicted in FIG. 1;

[0038]FIG. 3(a) is a sectional view taken along the line A-A′ of FIG. 2;

[0039]FIG. 3(b) is a sectional view taken along the line B-B′ of FIG. 2;

[0040]FIG. 4(a) is a front view of a fin depicted in FIG. 2;

[0041]FIG. 4(b) is a rear view of a fin depicted in FIG. 2;

[0042]FIG. 5 is a perspective view of a heat exchanger according to afirst embodiment of the present invention;

[0043]FIG. 6 is a perspective view of a fin depicted in FIG. 5;

[0044]FIG. 7 is a sectional view taken along the line C-C′ of FIG. 6;

[0045]FIG. 8(a) is a front view of a fin depicted in FIG. 6;

[0046]FIG. 8(b) is a rear view of a fin depicted in FIG. 6;

[0047]FIGS. 9 and 10 are views illustrating modified examples similar tothat depicted in FIG. 7;

[0048]FIGS. 11 and 12 are views illustrating airflow states in a heatexchanger according to a first embodiment of the present invention;

[0049]FIG. 13 is a perspective view of a fin of a heat exchangeraccording to a second embodiment of the present invention;

[0050]FIG. 14 is a sectional view taken along the line D-D′ of FIG. 13;

[0051]FIG. 15(a) is a front view of a fin depicted in FIG. 13;

[0052]FIG. 15(b) is a rear view of a fin depicted in FIG. 13;

[0053]FIG. 16 is a sectional view of a modified example similar to thatdepicted in FIG. 14;

[0054]FIGS. 17 and 18 are views illustrating airflow states in a heatexchanger according to a second embodiment of the present invention;

[0055]FIG. 19 is a perspective view of a heat exchange according to athird embodiment of the present invention;

[0056]FIG. 20 is a perspective view of a fin depicted in FIG. 19;

[0057]FIG. 21(a) is a sectional view taken along the line E-E′ of FIG.20;

[0058]FIG. 21(b) is a sectional view taken along the line F-F′ of FIG.20;

[0059]FIG. 21(c) is a sectional view taken along the line G-G′ of FIG.20;

[0060]FIG. 22(a) is a front view of a fin depicted in FIG. 20;

[0061]FIG. 22(b) is a rear view of a fin depicted in FIG. 20;

[0062]FIGS. 23 and 24 are views illustrating airflow states in a heatexchanger according to a third embodiment of the present invention; and

[0063]FIG. 25 is a graph illustrating a pressure drop and a heatcapacity of a heat exchanger according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0064] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

FIRST EMBODIMENT

[0065] FIGS. 5 to 12 show a first embodiment of the present invention.

[0066] Referring to FIGS. 5 to 7, the heat exchanger 101 according tothe first embodiment of the present invention includes a plurality offins 110 spaced away from each other at a predetermined distance and aplurality of tubes 130 disposed penetrating the fins 110 at right anglesand along which a refrigerant flows.

[0067] Here, the fin 110 includes at least four peak portions 112 and atleast five valley portions 114 formed inclined at a predetermined angleand continuously formed intersected with each other, fin collars 116formed defining tube insertion holes 116 a through which the tubes 130perpendicularly pass, seats 118 for supporting the tubes 130, andinclined portions 120 inclined upwardly from outer circumferences of theseats 118 to the peak portions 112.

[0068] In the fin 110, at least four peak portions 112 (112 a, 112 b,112 c and 112 d) and at least five valley portions 114 (114 a, 114 b,114 c, 114 d and 114 e) are alternately formed between the fin collars116 and are connected to each other by surfaces inclined at apredetermined inclined angle.

[0069] As a feature of the present invention, the heights of the secondand third peak portions 112 b and 112 c are lower than those of thefirst and fourth peak portions 112 a and 112 d to more effectively guideair flowing between the tubes up to rear ends of the tubes 30.

[0070] The operational effect of the heat exchanger according to thefirst embodiment of the present invention will be described hereinafter.

[0071] As shown in FIGS. 5 to 8, the heat exchanger 301 is a fin-tubetype in which a plurality of corrugate fins each formed in a W-shape areperpendicularly disposed with respect to the tubes 130 and spaced awayfrom each other at a predetermined distance.

[0072] Each of the fins 110 is divided into a fin collar area throughwhich the tubes 130 penetrate and an inclined surface area definedbetween the fin collars 116. The heights and depths of the peak portionsand valley portions are different from each other to let the flow of theair introduced into the heat exchanger changed.

[0073] That is, inclined angles of the inclined surfaces connecting thealternately disposed peak portions 112 (112 a, 112 b, 112 c and 112 d)and valley portions 114 (114 a, 114 b, 114 c and 114 d) are differentfrom each other. For the more effective air incoming and outgoingoperation, the fin 110 is configured to have both side ends defined bythe first and fifth valley portions 114 a and 114 e. That is, the fin110 starts with the valley portion 114 a and ends with the valleyportion 114 e in a lateral direction.

[0074] In addition, the fin 110 is formed symmetrical based on thecenter valley portion 114 c. That is, the left and right portions basedon the central valley portion 114 c are symmetrical, and the heights anddepths of the peak portions and valley portions formed on each of theleft and right portions are different from each other.

[0075] The valley portions 114 a-114 e are located on an identicalhorizontal plane, and the peak portions 112 a-112 d are located on adifferent horizontal plane.

[0076] The first valley portion 114 a is defined by one side end of thefin, and the second valley portion 114 b is located between the firstand second peak portions 112 a and 112 b. The third valley portion 114 cis located between the second and third peak portions 112 b and 112 c,and the fourth valley portion 114 d is located between the third andfourth peak portions 112 c and 112 d. The fifth valley portion 114 e isdefined by the other side end of the fin.

[0077] At this point, the heights of the inner peak portions 112 b and112 c are different from those of the outer peak portions 112 a and 112d.

[0078] That is, as shown in FIGS. 6 and 7, the valley portions 113 arelocated on the identical horizontal plane, and the peak portions 112 arelocated in different heights H11, H12 and H13.

[0079] As shown in FIGS. 6 and 7, the valley portions are located on theidentical horizontal plane, the left and right portions based on thecenter valley portion 114 c are symmetrical, and the heights and depthsof the peak portions and valley portions formed on each of the left andright portions are different from each other.

[0080] For example, the heights H12 and H13 from the horizontal planewhere the valley portions 114 are located to the inner peak portions 112b and 112 c are lower than the heights H11 from the horizontal plane tothe outer peak portions 112 a and 112 d.

[0081] That is, the heights H11 of the first and fourth peak portions112 a and 112 d are identical to each other, and the heights H12 and H13of the inner peak portions 112 b and 112 c are also identical to eachother but lower than those of the outer peak portions 112 a and 112 d.Here, the distance between the inner peak portions can be narrower thanthat between the outer peak portion and the adjacent inner peak portion.

[0082] By the above-described structure, the airflow of the airintroduced into areas defined between the fins 110 is greatly variedwhen compared with the conventional art. Therefore, the air can be moreeffectively guided up to the rear ends of the tubes 30. In addition, thepressure drop is reduced for the high-speed airflow and an amount of theheat transfer is increased.

[0083] Specifically, when the heights H11 from the horizontal planewhere the first valley portion 114 a is located to the first and fourthpeak portions 112 a and 112 d are identical to each other, the heightsH12 and H13 from the horizontal plane where the second valley portion114 b is located to the second and third peak portions 112 b and 112 care lower than the heights H11 of the first and fourth peak portions 112a.

[0084] Alternatively, the heights H12 and H13 are designed to be greaterthan the height H11, or the height H11 is designed to be greater thanthe height H12 while the height H12 is greater than the height H13.

[0085] The heights H12 and H13 of the peak portions 112 b and 112 cshould not be higher than the heights H11 of the outermost peak portions112 a and 112 d. For example, although the heights H11 of the first andfourth peak portions 112 a and 112 d are higher than the heights H12 andH13 of the second and third peak portions 112 b and 112 c, it issatisfied if only the respective heights are different from each other.Accordingly, the heat exchanger of the present invention reduces thepressure drop and increases the amount of heat transfer when comparedwith the conventional heat exchanger having a fin that is designed suchthat the heights H11, H12 and H13 are identical to each other.

[0086] Alternatively, the peak portions 112 may be located on anidentical horizontal plane, and depths of the inner valley portions 114b, 114 c and 114 d may be lower than those of the outer valley portions114 a and 114 d. In addition, among the depths of the inner valleyportions 114 b, 114 c and 114 d, the depth of the center valley portion114 c may be lower than other depths.

[0087] Alternatively, it is also possible that the heights from areference horizontal plane to the peak portions are gradually reduced asthey go toward a longitudinal center portion of the fin or the depthsfrom a reference horizontal plane to the valley portions are graduallyreduced as they go toward the longitudinal center portion of the fin.

[0088] Meanwhile, the fin collars 116 are formed on the fin 110 and arearranged in a longitudinal direction of the fin 110. All of the centralaxes perpendicularly meet the longitudinal center portion of the fin110. The fin collars 116 define tube insertion holes 116 a each having adiameter corresponding to an outer diameter of the tube to support thetube 130 inserted therein.

[0089] In addition, the seat 118 formed around a lower end of an outercircumference of the fin collar 116 has a predetermined width to supportthe fin collar 116. The seat 118 is disposed on a horizontal planeidentical to that where the second, third and fourth valley portions 114b, 114 c and 114 c are located.

[0090] The inclined portions 120 are inclined upwardly from outercircumferences of the seat to the peak portions 112. That is, each ofthe inclined portions 120 is defined by connecting each of the peakportions 112 b and 112 c to the valley portions 114 b and 114 c or 114 cand 114 d contacting the outer circumference of the seat 118 andadjacent to the peak portions 112 b and 112 c, thereby being formed in atriangular-shape. The inclined portions 120 guide the air to flow alongthe outer circumference of the fin collars 116.

[0091] In addition, the inclined portions 120 may be further formed byconnecting two points of each outer peak portion (the first and secondpeak portions 112 a and 112 d) to two points of each inner adjacentvalley (the second and fourth valleys 114 b and 114 d) contacting theseat 118. In this case, the inclined portions 120 are formed in arectangular shape. The inclined portions 120 function as a wallenclosing the fin collar 116.

[0092] FIGS. 8(a) and 8(b) respectively show front and rear views of thefin according to the first embodiment of the present invention. The peakportions and the valley portions that are depicted in FIG. 8(a) becomethe valley portions and the peak portions in FIG. 8(b), respectively.That is, when being viewed in FIG. 8(b), the depths from the horizontalplane where the peak portions are located to the valley portions aredifferent from each other.

[0093]FIG. 9 shows a modified example of the first embodiment.

[0094] In this modified example, first, second, third and fourth peakportions 152 (152 a, 152 b, 152 c and 152 d) are located on an identicalhorizontal plane. The depths from the horizontal plane to valleyportions 154 are gradually increased as they go from the center portionof the fin to both side ends of the fin. That is, the depths H12′ of thesecond and fourth valley portions 154 b and 154 d are greater than thatH13′ of the third (center) valley portion 154 c, and the depths H11′ ofthe first and fifth valley portions 154 a and 154 e are greater than thedepth H12′. In this modified example, a seat disposed around a lower endof an outer circumference of a fin collar 156 may be located on ahorizontal plane different from horizontal planes where the valleyportions are located.

[0095]FIG. 10 shows another modified example of the first embodiment.

[0096] In this modified example, first, second, third and fourth peakportions 162 (162 a, 162 b, 162 c and 162 d) are located on an identicalhorizontal plane, depths H14 from the horizontal plane to inner valleyportions 164 b, 164 c and 164 d are identical to each other. Inaddition, depths H11 from the horizontal plane to outer valley portionsare greater than the depth H14. In this modified example, a seatdisposed around a lower end of an outer circumference of a fin collar156 may be located on a horizontal plane different from horizontalplanes where the valley portions are located.

[0097] In the above-described first embodiment, since the peak or valleyportions are configured to have a different height or depth, acontacting area with the air is increased, increasing the airflowvariation.

[0098] Although the fin is designed in a variety of structures, it ispreferable that the heights or depths of the inner peak and valleyportions are lower than those of the outer peak and valley portions.

[0099]FIGS. 11 and 12 show an airflow state of the heat exchangeraccording to the first embodiment. FIG. 11 is a case where the fin isformed of a single fin structure, and FIG. 12 is a case where the fin isformed of a dual fin structure.

[0100] As shown in FIG. 11, when outer air is introduced into the heatexchanger, since the air quickly flows between the tubes while itrepeatedly ascends and descends along the peak and valley portions 112(112 a, 112 b, 112 c and 112 d) and 114 (114 a, 114 b, 114 c and 114 d),the contacting area between the air and the fins is increased.

[0101] That is, the air is introduced through the first peak portion 112a. The flow of the air introduced through the first peak portions 112 ais varied as it further flows along the second and third peak portions112 b and 112 c. As a result, the airflow speed is increased, therebyincreasing the heat transfer efficiency.

[0102] Furthermore, since the heights H11 of the first and fourth peakportions 112 a and 112 d that are located on inlet and outlet sides ofthe air, respectively, are higher than those H12 and H13 of the secondand third peak portions 112 b and 112 c, the distance between theadjacent fins 110 is increased to thereby increase the air passage area.As a result, the pressure drop is reduced for the high-speed airflow tothereby increase the amount of heat transfer and reduce the overallpressure drop of the heat exchanger.

[0103] In addition, since the fin collars, seats and inclined portionsare formed around the tube insertion holes through which the tube isinserted, the air can be guided up to the rear end of the tube along thecurvatures of the tube and the inclined portions.

[0104] Specifically, when the air passes between the tubes 130 at ahigh-speed, the high-speed airflow increases the heat transfer andretards the growth of the frost layer. Accordingly, a high level of heatcapacity is maintained even under the frost forming condition, therebyincreasing the heat exchange capability and making it possible to runthe heat exchanger for many hours.

[0105]FIG. 12 shows an airflow state when the fins are formed in a dualfin structure and the tubes are perpendicularly installed on the fins ina zigzag-shape. Since the tubes are arranged in the zigzag-shape, whenthe air passes through a tube area and a none-tube area (area betweenthe tubes), the airflow is realized as in the case where the fin isformed of a single fin plate.

[0106] In the above-described first embodiment, since the heights ordepths of the inner peak and valley portions are lower than those of theouter peak and valley portions that are disposed on inlet and outletsides of the air, the air can quickly flow between the tubes, the aircan be effectively guided up to the rear end of the tube. In addition,since the pressure drop is reduced for the fast flow speed of the airflowing between the tubes while the heat transfer amount and heatexchange amount are increased, thereby improving the overall efficiencyof the heat exchanger.

SECOND EMBODIMENT

[0107] FIGS. 13 to 18 show a second embodiment of the present invention.

[0108] Referring to FIG. 13, a fin 210 includes first and second peakportions 212 (212 a and 212 b), first, second and third valley portions214 (214 a, 214 b, and 214 c). The first and third valley portions 214 aand 214 c are defined by both side ends of the fin, and the secondvalley portion 214 b is formed between the peak portions 212 a and 212b.

[0109] The first, second and third valley portions 214 a, 214 b and 214c are located on an identical horizontal plane. The second valleyportion 214 b has a predetermined width.

[0110] Describing more in detail with reference to FIG. 14, the peakportions 212 and the valleys 214 are alternately disposed. Heights H21from the horizontal plane to the peak portions 121 are identical to eachother.

[0111] The second valley portion 214 b is formed on a longitudinalcenter portion of the fin between the first and second peak lines 214 aand 214 b. The second valley portion 214 b is flat with thepredetermined width W. The width is less than an outer diameter of thetube 230 but greater than an inner diameter of the tube. The tube 230 isdisposed such that central axes of the tube 230 perpendicularlypenetrate a longitudinal centerline of the second valley portion 214 b.

[0112] As the flat-shaped valley portion 214 b is formed between thepeak portions 212 a and 212 b, a distance between the adjacent fins isincreased, thereby increasing the air passage area.

[0113] Furthermore, the air passing through between the adjacent tubes230 can be effectively guided up to the rear end of the tube 230. Inaddition, the pressure drop is reduced against the fast airflow speedand an amount of the heat transfer is increased.

[0114] Fin collars 216 defining tube insertion holes in which the tube230 is inserted are formed on and elevated from the second valleyportions 214 b to support the tube 230.

[0115] Seats 218 are formed around a lower end of an outer circumferenceof the fin collar 216 to allow the air to flow in the form of enclosingthe tube 30 and the fin collar 16. Inclined portions 220 are formed onthe fin 20 around the seats 218 to prevent the air flowing around thetubes 230 from getting out of a circumference of the tube 230. Theinclined portions 220 are inclined upward from the seat 218 to the peakportions 212 a and 212 b.

[0116] The seats 218 function as a passage communicating the secondvalley portion 214 b disposed on a longitudinal direction.

[0117] Preferably, the width W of the second valley portion 214 is setas a value that can maximize the frost forming retardation effect undera frost forming condition while minimizing the deterioration of the heattransfer efficiency. For example, when the outer diameter of the fincollar 216 is Wo and the width of the second valley portion 214 is W, itis preferable that the following condition is satisfied.

1.0>W/Wo>0.3.

[0118]FIG. 16 shows a modified example of the second embodiment.

[0119] In this modified example, a depth H22′ of a flat-shaped secondvalley portion 254 formed between first and second peak portions 252 aand 252 b is lower than depths H21′ of first and second valley portions254 a and 254 c.

[0120] In case the heights H21 of the peak portions 252 a and 252 b ishigher than the depth of the second valley portion 254 b, the depth H22′of the second valley portion 254 is lower than the heights of the peakportions 252 a and 252 b and higher than the depths of the first andthird valley portions 254 a and 254 c. The depths of the first and thirdvalley portions 254 a and 254 c are identical to each other.

[0121]FIGS. 17 and 18 show an airflow state of the heat exchangeraccording to the second embodiment.

[0122] Referring to FIG. 17, air comes in through the first valleyportion 214 a and goes out through the third valley portion 214 c.

[0123] When the air comes in, the air flows around the tube 230 with theincreased speed between a narrow gap between the tubes 230. However, thepressure of the air is dropped and the flow resistance is increased.

[0124] At this point, the distance between the adjacent fins 210 isincreased by the flat-shaped second valley portion 214 formed betweenthe first and second peak portions 212 a and 212 b to thereby increasethe air passage area. When the air passage area is increased, thepressure drop is reduced while the air still flows with the high speed.That is, the heat transfer is reduced in a high-speed airflow area whencompared with a case where the flat-shaped valley portion is not formed.This results in retarding the growth of the frost layer. Accordingly, ahigh heat capacity can be maintained under the frost forming conditionand the heat exchange capacity is increased, thereby making it possibleto run the heat exchanger for many hours.

[0125] In addition, when the frost is molten, the molten liquid flowstoward the flat-shaped valley portion between the tubes, which is thendropt to a lower end of the heat exchanger, thereby improving the drainefficiency of the molten liquid.

[0126]FIG. 18 shows an airflow state when the fins are formed in a dualfin structure.

[0127] As another modified example, it is possible to combine the firstand second embodiments. That is, four peak portions and five valleyportions are formed, and the center valley portion is formed in aflat-shape.

[0128] As still another modified example, the fins of the first andsecond embodiments are alternately disposed.

[0129] As still yet another modified example, when the fin is formed ona dual fin structure, the first and second embodiments can berespectively applied to left and right portions of the dual finstructure.

THIRD EMBODIMENT

[0130] FIGS. 19 to 25 show a third embodiment of the present invention.

[0131] Referring to FIGS. 19 to 21, a heat exchanger 301 includes: aplurality of fins 310 each having at least two peak portions 312 and atleast two valley portion 114 that are alternately disposed; a pluralityof tubes 330 disposed penetrating the fins 310 at right angles; fincollars 316 for fixing the tubes 330 inserted through the fins 310;seats 318 each formed around a lower end of an outer circumference ofeach fin collar 316; and inclined portions 320 inclined upwardly fromouter circumferences to the peak portions 312 to prevent air flowingaround the tubes 330 from getting away from a circumference of the tubes330.

[0132] The fin 310 is formed in a W-shape to define the three valleyportions 314 (314 a, 314 b and 314 c) and the two peak portions 312 (312a and 312 b) that are respectively formed between the valley portions314 a and 314 b and between the 414 b and 341 c. The peak portions 312 aand 312 b are located on an identical horizontal plane. A depth H32 fromthe horizontal plane to the center (second) valley portion 114 b islower than those H31 from the horizontal plane to the fist and thirdvalley portions 114 a and 114 c.

[0133] In addition, heights of the peak portions 312 a and 312 b arealmost identical to a height of a top of the fin collar 316 defining atube insertion hole 316 a through which the tube is inserted.

[0134] The inclined portions 320 are formed extending from an outercircumference of the seat 318 formed around the lower end of the outercircumference of the fin collar 316 to the peak portions 312, therebypreventing the air flowing around the tube 330 from getting out of thecircumference of the tube 330.

[0135] That is, since the seats 318 are located on a horizontal planeidentical to that where the first and second valley portions arelocated, the seats 318 are connected to the peak portions 312 at apredetermined curvature angle from the valley portions to the peakportions in a lateral direction and from the peak portion to the peakportion in a longitudinal direction.

[0136] Here, the depth H32 of the second valley portion 314 b is lowerthan the depth H31 of the peak portion 312. The ratio of the depth H32to the depth H31 (H32/H31) should be equal to or lower than 0.7 toreduce the pressure drop against the fast flow speed of the air.Alternatively, the depth H32 of the second valley portion 314 b can bedesigned to be greater or less than the heights H31 of the peaks 312.

[0137] In order to design the depth H32 of the second valley portion 314b to be less than the heights H32 of the peak portions 312, inclinedangles of the both side surfaces of the peak portions 312 are designedto be different from each other. That is, the inclined angles of outersides of the peak portions 312 are greater than those of inner sides ofthe peak portions 312, which are connected to the second valley portion314 b, inside angles of the peak portions 312 become naturally smallerthan the inner angle of the second valley 314 b.

[0138] As described above, when the heights H31 of the peak portions 312is greater than the depth of the second valley portion 314 b, the secondvalley is located on a horizontal plane between the horizontal planewhere the peak portions 312 are located and the horizontal plane wherethe seat is located.

[0139] FIGS. 22(a) and 22(b) respectively show front and rear views ofthe fin depicted in FIG. 20.

[0140]FIGS. 23 and 24 show an airflow state of the heat exchangeraccording to the third embodiment.

[0141] Referring to FIG. 23, when air comes into the heat exchanger, theflow speed of the air is increased between the tubes. However, becauseof the seats 318 and the height and depth difference between the peakand valley portions, the air resistance is reduced while the air can beguided to the rear end of the tube 330 along the inclined portions 320and the seats 318.

[0142]FIG. 25 shows a graph illustrating a pressure drop and a heatcapacity of a heat exchanger according to the present invention.

[0143] As shown in FIG. 25, since the heights of the peak portions 312are greater than the depth of the valley portion 314 b, a distancebetween the adjacent fins 310 is increased. As a result, the pressuredrop of the air is reduced against the fast flow speed of the air.Furthermore, since a relatively high heat capacity can be maintainedeven under a frost forming condition, the heat exchanger can be operatedfor many hours.

[0144] As described in the above embodiments, the pressure drop can bereduced by forming the depth of the valley portion higher than theheight of the peak portion, thereby improving the heat exchangeefficiency. Further, the airflow around the tubes can be effectivelyguided to the rear portions of the tubes by installing the inclinedportion in the inclined surface between the valley portion and the fincollar.

[0145] As described above, the airflow areas between the front and rearfins are increased by forming the peak and valley portions which areinclined and have different heights, thereby reducing the pressure drop.Additionally, an amount of the heat transfer amount is increased tothereby improve the overall efficiency of the heat exchanger.

[0146] Further, the pressure drop is decreased due to the change in theair flow by forming the flat-shaped valley portion having thepredetermined width (area) between the peak portions. As a result, anamount of the heat transfer is increased and the overall efficiency ofthe heat exchanger is improved.

[0147] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A heat exchanger comprising: a plurality of tubesthrough which refrigerants flow, the tubes being spaced away from eachother; and a plurality of fins through which the tubes areperpendicularly inserted, the fins being spaced away from each other ata predetermined distance, each of the fin having more than four peakportions and more than four valley portions that are alternatelydisposed, heights or depths of at least two peak portions or at leasttwo valley portions being different from each other.
 2. The heatexchanger according to claim 1, wherein the fin is a corrugate finhaving an inversed W-shape.
 3. The heat exchanger according to claim 1,wherein heights from a horizontal plane, where one of the valleyportions is located, to the peak portions are different from each other.4. The heat exchanger according to claim 1, wherein depths from ahorizontal plane, where one of the peak portions is located, to thevalley portions are different from each other.
 5. The heat exchangeraccording to claim 1, wherein the valley portions are located on ahorizontal plane, and heights from the horizontal plane to the peakportions are different from each other.
 6. The heat exchanger accordingto claim 5, wherein among the peak portions, the outer peak portionshave a first height and the inner peak portions have a second height,the first height being different from the second height.
 7. The heatexchanger according to claim 1, wherein the peak portions are located ona horizontal plane, and depths from the horizontal plane to the valleyportions are different from each other.
 8. The heat exchanger accordingto claim 7, wherein among the valley portions, the outer valley portionshave a first depth and the inner valley portions have a second depth,the first depth being different from the second depth.
 9. The heatexchanger according to claim 1, wherein a longitudinal centerline of thepin is defined by one of the valley portions, the pin having left andright halves that are symmetrical based on the longitudinal centerline,the heights and depths of the peak and valley portions being increasedas they go to an outer side.
 10. The heat exchanger according to claim6, wherein the first height is greater than the second height.
 11. Theheat exchanger according to claim 1, wherein each of the fins comprises:a plurality of fin collars disposed along a longitudinal centerline ofthe fin, each of the fin collar being elevated to a predetermined heightto define a tube insertion hole through which the tube is inserted; aplurality of seats each disposed on a lower end of an outercircumference of the fin collar; and an airflow guide portion formedextending from an outer circumference of the seat to the peak potions ata predetermined angle to allow air to flow along an outer circumferenceof the tube.
 12. The heat exchanger according claim 11, wherein theseats are located on a horizontal plane identical to that where thevalley portions are located, the seat having a predetermined width. 13.A heat exchanger comprising: a plurality of tubes through whichrefrigerants flow, the tubes being spaced away from each other; and aplurality of fins spaced away from each other at a predetermineddistance, each of the fin including a fin collar through which tube isperpendicularly inserted, a seat disposed around an outer circumferenceof the fin collar, and peak and valley portions alternately disposed,inclined angles of portions connecting the peaks with the valleys beingdifferent from each other.
 14. The heat exchanger according to claim 13,further comprising an airflow guide portion formed extending from anouter circumference of the seat to the peak potions at a predeterminedangle to prevent air from getting out of a circumference of the tube.15. A heat exchanger comprising: a plurality of tubes through whichrefrigerants flow, the tubes being spaced away from each other; and aplurality of fins spaced away from each other at a predetermineddistance, each of the fin including a fin collar through which tube isperpendicularly inserted, a seat disposed around an outer circumferenceof the fin collar, and peak and valley portions alternately disposed, atleast one of the valley portions being formed between the peak portionsin a flat shape having a predetermined width.
 16. The heat exchangeraccording to claim 15, wherein the valley portion formed in the flatshape is located on a horizontal plane identical to that where the restof the valleys are located.
 17. The heat exchanger according to claim15, wherein the valley portion formed in the flat shape is located on ahorizontal plane higher than that where the rest of the valleys arelocated.
 18. The heat exchanger according to claim 15, wherein thevalley portion formed in the flat shape is located on a horizontal planeidentical to that where the seat disposed around the fin collar islocated.
 19. The heat exchanger according to claim 15, wherein a widthWo of the valley portion formed in the flat shape is determined suchthat the following condition is satisfied, 1.0>Wo/D>0.3 where, the D isan outer diameter of the fin collar.
 20. A heat exchanger comprising: aplurality of tubes through which refrigerants flow, the tubes beingspaced away from each other; and a plurality of fins spaced away fromeach other at a predetermined distance, each of the fin including a fincollar through which tube is perpendicularly inserted, a seat disposedaround an outer circumference of the fin collar, peak and valleyportions alternately disposed, inclined portions extending from an outercircumference of the seat to the peak portions.
 21. The heat exchangeraccording to claim 20, wherein the seat is located on a horizontal planelower than that where the valley portions are located.
 22. A heatexchanger comprising: a plurality of tubes through which refrigerantsflow, the tubes being spaced away from each other; and a plurality offins each having fin collars through which the tubes are perpendicularlyinserted and peak and valley portions that are alternately disposed,heights and depths of the outer peak and valley portions being differentfrom those of the inner peak and valley portions.
 23. The heat exchangeraccording to claim 22, wherein the adjacent tubes are inserted into thefin collars in a zigzag shape.
 24. The heat exchanger according to claim22, wherein a ratio of the depths of the valley portions to the heightsof the peak portions is equal to or less than 0.7.